This is obviously much bigger than the leak of some classified documents that expose secret surveilance programs. The reaction of the US government (in this case, the decisions are probably made by Obama himself) is a lot bigger than a random criminal prosecution.

Just look at the measures taken in order to intimidate or capture Snowden: In effect, the US government grounded the private jet of a foreign head of state. If a similar action was done against the US, it would be considered an act of war. A persecution is exactly what this is, under the plausible (even legal) guise of criminal proceedings.